PokerTracker

what is a difference between stats (Bet) and (Bet%)???

"Bet%" is a stat built for the legacy "Details" report - it is the percentage of actions which were bets.
Bet% = bets / (checks+folds+calls+bets+raises)

"Bet" is the percentage of times that the player bet when they had the opportunity. This is a better measure because it only counts the times that you could actually bet - if your opponent opens the flop before you have a chance to act then you can't bet, and this stat doesn't count that as an opportunity.
Bet = bets / checks + bets

You can see exactly how any stat is calculated by looking at Configure > Configure Stats.
See the Tutorial: Custom Reports and Statistics for information on how stats are constructed.